This invention relates to an induction system for an internal combustion engine and more particularly to an improved method and structure for controlling the engine induction.
Internal combustion engines, particularly those used in automotive applications, are called upon to run over a wide variety of speed and load ranges. As a result, many features in the engine design, particularly the induction and fuel feed system, require compromise to suit all load and speed conditions. As a result, low speed performance normally requires sacrifice of either fuel economy or smoothness of running or both. To offset these disadvantages, it has been proposed to provide an induction system employing a relatively large main induction passage and a relatively small auxiliary induction passage. The flow through these passages to the combustion chambers is controlled in such a way that substantially all of the low and partial load charge requirements are delivered to the chamber through the relatively smaller auxiliary induction passage. This permits the establishment of high turbulence in the chamber at the time of combustion to improve flame propogation and combustion. This is accomplished without the sacrifice of maximum power output and volumetric efficiency due to the use of the large main induction passage.
In accordance with this principle, it has been found that it is extremely important to accurately control the transition point at which flow transfers from the auxiliary to the main induction passage. It is, therefore, a first object of this invention to provide an improved flow control arrangement for an engine having a split induction system.
It is another object of the invention to provide an improved throttle control arrangement for an internal combustion engine having main and auxiliary induction passages.
In accordance with standard throttle valve arrangements, the use of two throttle valves in a given passage considerably increases the spacial requirements of the induction system. It is, therefore, a further principle object of the invention to provide an improved compact throttle valve arrangement.
It is a yet further object of the invention to provide a throttle valve system in which two butterfly-type throttle valves may be compactly positioned in a given conduit.